How to properly set up this PBR texture
The normal texture needs to go tough the Normal Map node. The texture data is normalised so the normal vector is between 0 and 1 (0.5 as mid value) for each channel. This needs to be recalculated to be in the range from -1 to 1 (0 as mid value). It will also convert the tangent space vector to world space.



If you need to scale the UV coordinates, the Mapper node should change the values from the UV Map node. UV coordinates are usually 2-dimensional where a texture always are within 0 - 1 range. If you go outside this range the texture gets repeated if the Texture node is set to Repeat.



But the simplest way is just to scale the UV coordinates in the UV Editor.
It does not matter if the islands are overlapping (unless they are used for baking) or exceeds the texture boundaries (if the texture is tiling). In fact, tiling textures are made to work this way.